Does Docsis Have a 5-Gig Future?
Once MSOs get an opportunity to use their full slate of spectrum for IP, "we can see how to get to 5Gbit/s down and 1Gbit/s up," said John Chapman, CTO of Cisco's cable access business unit and a Cisco fellow, during his Tuesday keynote here.
He didn't say when that would happen, but it would be more than a quantum leap from where things stand today. Current-generation Docsis 3.0 gear can bond eight downstream channels and four upstream channels -- enough for more than 300Mbit/s down and 100Mbit/s up. Within a year, Chapman sees the advent of cable modem models that can bond 24 channels, giving cable the potential for 1Gbit/s downstream bursts.
"Docsis is just a teenager in many ways," Chapman said, noting that cable is utilizing just 1 percent to 2 percent of its spectrum with the bonding of eight downstream channels. He believes MSOs will need to allocate about 20 Docsis channels to support a full IP video migration. Some industry experts think cable will probably need more. (See MSOs Must Bust Out Bandwidth for IP Video Leap.)
(The other way in which Doscis is a teenager is literal: It's turning 15. The 1.0 specifications were issued March 26, 1997, represented by a mere 172 pages.)
Docsis is far from being a reliable conduit for video services, Chapman warned. Prepping Docsis for managed IP-video services -- as opposed to today's unmanaged over-the-top video -- represents "the next technical challenge for our community," he said.
Chapman also stressed that Docsis doesn't compete with the EPON Over Coax (EPoC) standard being developed by the Institute of Electrical and Electronics Engineers Inc. (IEEE) . They use the same cable spectrum, but Docsis is primarily used for residential data, while EPoC will likely target business-class services at first, he said. (See Why Cable Needs EPON Over Coax and EPON-Over-Coax Starts Its Standards Journey .)
— Jeff Baumgartner, Site Editor, Light Reading Cable